Field of the Invention
This invention relates to the general field of audio systems, and more specifically toward an extendable speaker system.
Description of the Related Art
Speakers are considered by many to be a necessity for a variety of social functions, ranging from tailgates to wedding ceremonies. There is a demand for an appealing, portable speaker system that can play loud music with a balanced and wide frequency response.
Low frequency loudspeakers, such as a woofer or subwoofer speaker, use enclosures to prevent sound waves generated by the rearward-facing surface of the diaphragm of a speaker interacting with sound waves generated at the front of the speaker. The sound waves generated by the rearward-facing surface of a speaker are out of phase with the sound waves generated by the forward-facing surface, and therefore cause distorted sound when a listener hears both sets of sound waves. The enclosure that resides behind the speaker restricts or prevents sound waves from leaving the speaker system, thereby reducing or eliminating the sound waves that are out of phase.
There are two general types of enclosures produced for woofer speakers. A sealed enclosure provides for an airtight enclosure that reduces if not eliminates any out-of phase sound emanating from the speaker, A ported enclosure includes an opening (or port) that enables air and sound waves to pass therethough. A sealed enclosure may provide less distortion and crisper sound, but not provide the same “thunder” or “roar” as a ported enclosure. The airtight sealed enclosure acts as a type of shock absorber that restricts large displacements of the cone of the speaker. The ported enclosure removes the shock absorber effect, but does allow some sound to escape. This out of phase sound emanating from the enclosure can lead to an overall distorted sound to the user.
To mitigate the effects of the shock absorbing sealed enclosure, the sealed enclosure can be made larger. A larger sealed enclosure provides for smaller pressure changes resulting from the displacement of the cone of the speaker. Smaller pressure changes in the sealed enclosure allow for a greater displacement of the cone of the speaker, while reducing or preventing out of phase sound waves from leaving the speaker system. Larger ported enclosures are also beneficial over smaller ported enclosures, as the larger ported enclosures are able to trap and dissipate the out of phase sound more effectively than smaller sized ported enclosures.
Providing a large enclosure for a woofer speaker results in a large, often cumbersome, unit that is difficult to transport. Smaller sealed speaker enclosures, while easier to transport, don't provide the rich, tight sound at lower frequencies. Prior art speaker systems have tried to overcome these difficulties by providing inflatable sealed enclosures, or enclosures with flexible walls. However, these systems can be easily broken (punctured), don't expand to multiple times their collapsed size, or don't provide high quality sound at a wide range of frequencies.
Thus there has existed a long-felt need for a speaker system that provides high quality audio with a wide frequency response, including low frequencies, that can collapse to a small size for transport and storage, and expand to multiple times its collapsed size to provide a larger speaker enclosure.